server.js

const { createServer } = require("http");
const { parse } = require("url");
const next = require("next");
const WebSocketServer = require("ws").Server;
const child_process = require("child_process");
const url = require("url");

const port = parseInt(process.env.PORT, 10) || 3000;
const dev = process.env.NODE_ENV !== "production";
const app = next({ dev });
const handle = app.getRequestHandler();

app.prepare().then(() => {
  const server = createServer((req, res) => {
    const parsedUrl = parse(req.url, true);

    handle(req, res, parsedUrl);
  }).listen(port, (err) => {
    if (err) throw err;
    console.log(`> Ready on port ${port}`);
  });

  const wss = new WebSocketServer({
    server: server,
  });

  wss.on("connection", (ws, req) => {
    console.log("Socket connected");

    const queryString = url.parse(req.url).search;
    const params = new URLSearchParams(queryString);
    const key = params.get("key");

    const rtmpUrl = `rtmps://global-live.mux.com/app/${key}`;

    const ffmpeg = child_process.spawn("ffmpeg", [
      "-i",
      "-",

      // video codec config: low latency, adaptive bitrate
      "-c:v",
      "libx264",
      "-preset",
      "veryfast",
      "-tune",
      "zerolatency",

      // audio codec config: sampling frequency (11025, 22050, 44100), bitrate 64 kbits
      "-c:a",
      "aac",
      "-strict",
      "-2",
      "-ar",
      "44100",
      "-b:a",
      "64k",

      //force to overwrite
      "-y",

      // used for audio sync
      "-use_wallclock_as_timestamps",
      "1",
      "-async",
      "1",

      //'-filter_complex', 'aresample=44100', // resample audio to 44100Hz, needed if input is not 44100
      //'-strict', 'experimental',
      "-bufsize",
      "1000",
      "-f",
      "flv",

      rtmpUrl,
    ]);

    // Kill the WebSocket connection if ffmpeg dies.
    ffmpeg.on("close", (code, signal) => {
      console.log(
        "FFmpeg child process closed, code " + code + ", signal " + signal
      );
      ws.terminate();
    });

    // Handle STDIN pipe errors by logging to the console.
    // These errors most commonly occur when FFmpeg closes and there is still
    // data to write.f If left unhandled, the server will crash.
    ffmpeg.stdin.on("error", (e) => {
      console.log("FFmpeg STDIN Error", e);
    });

    // FFmpeg outputs all of its messages to STDERR. Let's log them to the console.
    ffmpeg.stderr.on("data", (data) => {
      ws.send("ffmpeg got some data");
      console.log("FFmpeg STDERR:", data.toString());
    });

    ws.on("message", (msg) => {
      if (Buffer.isBuffer(msg)) {
        console.log("Sent video data");
        ffmpeg.stdin.write(msg);
      } else {
        console.log(msg);
      }
    });

    ws.on("close", (e) => {
      console.log("Websocket closed");
      ffmpeg.kill("SIGINT");
    });
  });
});